Method and apparatus for overhead reduction of signaling messages

ABSTRACT

A method and apparatus to reduce the overhead of frequently sent signaling messages is provided. Various methods are presented which facilitate conveying information that is unchanged from information in the earlier part of the message, or in a previous signaling message, without sending the previous information in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/556,098, filed Nov. 2, 2006, now U.S. Pat. No. 7,672,644, whichclaims the benefit of U.S. Provisional Application Ser. Nos. 60/734,630filed on Nov. 7, 2005 and 60/733,017 filed on Nov. 2, 2005, the contentsof which are hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is related to a method and apparatus to reduce theoverhead of frequently sent signaling messages.

2. Description of the Related Art

In the world of cellular telecommunications, those skilled in the artoften use the terms 1G, 2G, and 3G. The terms refer to the generation ofthe cellular technology used. 1G refers to the first generation, 2G tothe second generation, and 3G to the third generation.

1G refers to the analog phone system, known as an AMPS (Advanced MobilePhone Service) phone systems. 2G is commonly used to refer to thedigital cellular systems that are prevalent throughout the world, andinclude CDMAOne, Global System for Mobile communications (GSM), and TimeDivision Multiple Access (TDMA). 2G systems can support a greater numberof users in a dense area than can 1G systems.

3G commonly refers to the digital cellular systems currently beingdeployed. These 3G communication systems are conceptually similar toeach other with some significant differences.

Referring to FIG. 1, a wireless communication network architecture 1 isillustrated. A subscriber uses a mobile station (MS) 2 to access networkservices. The MS 2 may be a portable communications unit, such as ahand-held cellular phone, a communication unit installed in a vehicle,or a fixed-location communications unit.

The electromagnetic waves for the MS 2 are transmitted by the BaseTransceiver System (BTS) 3 also known as node B. The BTS 3 consists ofradio devices such as antennas and equipment for transmitting andreceiving radio waves. The BS 6 Controller (BSC) 4 receives thetransmissions from one or more BTS's. The BSC 4 provides control andmanagement of the radio transmissions from each BTS 3 by exchangingmessages with the BTS and the Mobile Switching Center (MSC) 5 orInternal IP Network. The BTS's 3 and BSC 4 are part of the BS 6 (BS) 6.

The BS 6 exchanges messages with and transmits data to a CircuitSwitched Core Network (CSCN) 7 and Packet Switched Core Network (PSCN)8. The CSCN 7 provides traditional voice communications and the PSCN 8provides Internet applications and multimedia services.

The Mobile Switching Center (MSC) 5 portion of the CSCN 7 providesswitching for traditional voice communications to and from a MS 2 andmay store information to support these capabilities. The MSC 2 may beconnected to one or more BS's 6 as well as other public networks, forexample a Public Switched Telephone Network (PSTN) (not shown) orIntegrated Services Digital Network (ISDN) (not shown). A VisitorLocation Register (VLR) 9 is used to retrieve information for handlingvoice communications to or from a visiting subscriber. The VLR 9 may bewithin the MSC 5 and may serve more than one MSC.

A user identity is assigned to the Home Location Register (HLR) 10 ofthe CSCN 7 for record purposes such as subscriber information, forexample Electronic Serial Number (ESN), Mobile Directory Number (MDR),Profile Information, Current Location, and Authentication Period. TheAuthentication Center (AC) 11 manages authentication information relatedto the MS 2. The AC 11 may be within the HLR 10 and may serve more thanone HLR. The interface between the MSC 5 and the HLR/AC 10, 11 is anIS-41 standard interface 18.

The Packet Data Serving Node (PDSN) 12 portion of the PSCN 8 providesrouting for packet data traffic to and from MS 2. The PDSN 12establishes, maintains, and terminates link layer sessions to the MS 2's2 and may interface with one or more BS 6 and one or more PSCN 8.

The Authentication, Authorization and Accounting (AAA) 13 Serverprovides Internet Protocol authentication, authorization and accountingfunctions related to packet data traffic. The Home Agent (HA) 14provides authentication of MS 2 IP registrations, redirects packet datato and from the Foreign Agent (FA) 15 component of the PDSN 8, andreceives provisioning information for users from the AAA 13. The HA 14may also establish, maintain, and terminate secure communications to thePDSN 12 and assign a dynamic IP address. The PDSN 12 communicates withthe AAA 13, HA 14 and the Internet 16 via an Internal IP Network.

There are several types of multiple access schemes, specificallyFrequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA) and Code Division Multiple Access (CDMA). In FDMA, usercommunications are separated by frequency, for example, by using 30 KHzchannels. In TDMA, user communications are separated by frequency andtime, for example, by using 30 KHz channels with 6 timeslots. In CDMA,user communications are separated by digital code.

In CDMA, All users on the same spectrum, for example, 1.25 MHz. Eachuser has a unique digital code identifier and the digital codes separateusers to prevent interference.

A CDMA signal uses many chips to convey a single bit of information.Each user has a unique chip pattern, which is essentially a codechannel. In order to recover a bit, a large number of chips areintegrated according to a user's known chip pattern. Other user's codepatterns appear random and are integrated in a self-canceling mannerand, therefore, do not disturb the bit decoding decisions made accordingto the user's proper code pattern.

Input data is combined with a fast spreading sequence and transmitted asa spread data stream. A receiver uses the same spreading sequence toextract the original data. FIG. 2A illustrates the spreading andde-spreading process. As illustrated in FIG. 2B, multiple spreadingsequences may be combined to create unique, robust channels.

A Walsh code is one type of spreading sequence. Each Walsh code is 64chips long and is precisely orthogonal to all other Walsh codes. Thecodes are simple to generate and small enough to be stored in Read OnlyMemory (ROM).

A short PN code is another type of spreading sequence. A short PN Codeconsists of two PN sequences (I and Q), each of which is 32,766 chipslong and is generated in similar, but differently tapped 15-bit shiftregisters. The two sequences scramble the information on the I and Qphase channels.

A long PN code is another type of spreading sequence. A long PN Code sgenerated in a 42-bit register and is more than 40 days long, or about4×10¹³ chips long. Due to its length, a long PN code cannot be stored inROM in a terminal and, therefore, is generated chip-by-chip.

Each MS 2 codes its signal with the PN long code and a unique offset, orpublic long code mask, computed using its unique ESN (Electronic SerialNumber) of 32-bits and 10 bits set by the system. The public long codemask produces a unique shift Private long code masks may be used toenhance privacy. When integrated over as short a period as 64 chips, MS2 with different long PN code offsets will appear practicallyorthogonal.

CDMA communication uses forward channels and reverse channels. A forwardchannel is utilized for signals from a BTS 3 to a MS 2 and a reversechannel is utilized for signals from a MS to a BTS.

A forward channel uses its specific assigned Walsh code and a specificPN offset for a sector, with one user able to have multiple channeltypes at the same time. A forward channel is identified by its CDMA RFcarrier frequency, the unique short code PN offset of the sector and theunique Walsh code of the user. CDMA forward channels include a pilotchannel, sync channel, paging channels and traffic channels.

The pilot channel is a “structural beacon” which does not contain acharacter stream, but rather is a timing sequence used for systemacquisition and as a measurement device during handoffs. A pilot channeluses Walsh code 0.

The sync channel carries a data stream of system identification andparameter information used by MS 2 during system acquisition. A syncchannel uses Walsh code 32.

There may be from one to seven paging channels according to capacityrequirements. Paging channels carry pages, system parameter informationand call setup orders. Paging channels use Walsh codes 1-7.

The traffic channels are assigned to individual users to carry calltraffic. Traffic channels use any remaining Walsh codes subject tooverall capacity as limited by noise.

A reverse channel is utilized for signals from a MS 2 to a BTS 3 anduses a Walsh code and offset of the long PN sequence specific to the MS,with one user able to transmit multiple types of channelssimultaneously. A reverse channel is identified by its CDMA RF carrierfrequency and the unique long code PN offset of the individual MS 2.Reverse channels include traffic channels and access channels.

Individual users use traffic channels during actual calls to transmittraffic to the BTS 3. A reverse traffic channel is basically auser-specific Public or Private Long Code Mask and there are as manyreverse traffic channels as there are CDMA terminals.

An MS 2 not yet involved in a call uses access channels to transmitregistration requests, call setup requests, page responses, orderresponses and other signaling information. An access channel isbasically a public long code offset unique to a BTS 3 sector, Accesschannels are paired with paging channels, with each paging channelhaving up to 32 access channels.

CDMA communication provides many advantages. Some of the advantages arevariable rate vocoding and multiplexing, forward power control, use ofRAKE receivers and soft handoff.

CDMA allows the use of variable rate vocoders to compress speech, reducebit rate and greatly increase capacity. Variable rate vocoding providesfull bit rate during speech, low data rates during speech pauses,increased capacity and natural sound. Multiplexing allows voice,signaling and user secondary data to be mixed in CDMA frames.

By utilizing forward power control, the BTS 3 continually reduces thestrength of each user's forward baseband chip stream. When a particularMS 2 experiences errors on the forward link, more energy is requestedand a quick boost of energy is supplied after which the energy is againreduced.

Reverse power control uses three methods in tandem to equalize allterminal signal levels at the BTS 3. Reverse open loop power control ischaracterized by the MS 2 adjusting power up or down based on a receivedBTS 3 signal (AGC). Reverse closed loop power control is characterizedby the BTS 3 adjusting power up or down by 1 db at a rate of 800 timesper second. Reverse outer loop power control is characterized by the BSC4 adjusting a BTS 3 set point when the BSC has Forward Error Correction(FER) trouble hearing the MS 2.

The actual RF power output of the MS 2 transmitter (TXPO), including thecombined effects of open loop power control from receiver AGO and closedloop power control by the BTS 3, cannot exceed the maximum power of theMS, which is typically +23 dbm. Reverse power control is performedaccording to the equation “TXPO=−(RX_(dbm))−C+TXGA,” where “TXGA” is thesum of all Closed Loop power control commands from the BTS 3 since thebeginning of a call and “C” is +73 for 800 MHZ systems and +76 for 1900MHz systems.

Using a RAKE receiver allows a MS 2 to use the combined outputs of thethree or more traffic correlators, or “RAKE fingers,” every frame. EachRAKE finger can independently recover a particular PN offset and Walshcode, The fingers may be targeted on delayed multipath reflections ofdifferent BTS's 3, with a searcher continuously checking pilot signals.

The MS 2 drives soft handoff. The MS 2 continuously checks availablepilot signals and reports to the BTS 3 regarding the pilot signals itcurrently sees. The BTS 3 assigns up to a maximum of six sectors and theMS 2 assigns its fingers accordingly. Air interface messages are sent bydim-and-burst without muting. Each end of the communication link choosesthe best configuration on a frame-by-frame basis, with handofftransparent to users.

A cdma2000 system is a third-generation (3G) wideband; spread spectrumradio interface system that uses the enhanced service potential of CDMAtechnology to facilitate data capabilities, such as Internet andintranet access, multimedia applications, high-speed businesstransactions, and telemetry. The focus of cdma2000, as is that of otherthird-generation systems, is on network economy and radio transmissiondesign to overcome the limitations of a finite amount of radio spectrumavailability.

FIG. 3 illustrates a data link protocol architecture layer 20 for acdma2000 wireless network, The data link protocol architecture layer 20includes an Upper Layer 60, a Link Layer 30 and a Physical Layer 21.

The Upper Layer 60 includes three sublayers; a Data Services sublayer61; a Voice Services sublayer 62 and a Signaling Services sublayer 63.Data Services 61 are services that deliver any form of data on behalf ofa mobile end user and include packet data applications such as EPservice, circuit data applications such as asynchronous fax and B-ISDNemulation services, and SMS. Voice Services 62 include PSTN access,mobile-to-mobile voice services, and Internet telephony. Signaling 63controls all aspects of mobile operation.

The Signaling Services sublayer 63 processes all messages exchangedbetween the MS 2 and BS 6. These messages control such functions as callsetup and teardown, handoffs, feature activation, system configuration,registration and authentication.

In the MS 2, the Signaling Services sublayer 63 is also responsible formaintaining call process states, specifically a MS 2 InitializationState, MS 2 Idle State, System Access State and MS 2 Control on TrafficChannel State.

The Link Layer 30 is subdivided into the Link Access Control (LAC)sublayer 32 and the Medium Access Control (MAC) sublayer 31, The LinkLayer 30 provides protocol support and control mechanisms for datatransport services and performs the functions necessary to map the datatransport needs of the Upper layer 60 into specific capabilities andcharacteristics of the Physical Layer 21. The Link Layer 30 may beviewed as an interface between the Upper Layer 60 and the Physical Layer20.

The separation of MAC 31 and LAC 32 sublayers is motivated by the needto support a wide range of Upper Layer 60 services and the requirementto provide for high efficiency and low latency data services over a wideperformance range, specifically from 1.2 Kbps to greater than 2 Mbps.Other motivators are the need for supporting high Quality of Service(QoS) delivery of circuit and packet data services, such as limitationson acceptable delays and/or data BER (bit error rate), and the growingdemand for advanced multimedia services each service having a differentQoS requirements.

The LAC sublayer 32 is required to provide a reliable, in-sequencedelivery transmission control function over a point-to-point radiotransmission link 42. The LAC sublayer 32 manages point-to pointcommunication channels between upper layer 60 entities and providesframework to support a wide range of different end-to-end reliable LinkLayer 30 protocols.

The LAC sublayer 32 provides correct delivery of signaling messages.Functions include assured delivery where acknowledgement is required,unassured delivery where no acknowledgement is required, duplicatemessage detection, address control to deliver a message to an individualMS 2, segmentation of messages into suitable sized fragments fortransfer over the physical medium, reassembly and validation of receivedmessages and global challenge authentication.

The MAC sublayer 31 facilitates complex multimedia, multi-servicescapabilities of 3G wireless systems with QoS management capabilities foreach active service. The MAC sublayer 31 provides procedures forcontrolling the access of packet data and circuit data services to thePhysical Layer 21, including the contention control between multipleservices from a single user, as well as between competing users in thewireless system. The MAC sublayer 31 also performs mapping betweenlogical channels and physical channels, multiplexes data from multiplesources onto single physical channels and provides for reasonablyreliable transmission over the Radio Link Layer using a Radio LinkProtocol (RLP) 33 for a best-effort level of reliability. SignalingRadio Burst Protocol (SRBP) 35 is an entity that provides connectionlessprotocol for signaling messages. Multiplexing and QoS Control 34 isresponsible for enforcement of negotiated QoS levels by mediatingconflicting requests from competing services and the appropriateprioritization of access requests.

The Physical Layer 21 is responsible for coding and modulation of datatransmitted over the air. The Physical Layer 21 conditions digital datafrom the higher layers so that the data may be transmitted over a mobileradio channel reliably.

The Physical Layer 21 maps user data and signaling, which the MACsublayer 31 delivers over multiple transport channels, into a physicalchannels and transmits the information over the radio interface. In thetransmit direction, the functions performed by the Physical Layer 21include channel coding, interleaving, scrambling, spreading andmodulation. In the receive direction, the functions are reversed inorder to recover the transmitted data at the receiver.

FIG. 4 illustrates an overview of call processing. Processing a callincludes pilot and sync channel processing, paging channel processing,access channel processing and traffic channel processing.

Pilot and sync channel processing refers to the MS 2 processing thepilot and sync channels to acquire and synchronize with the CDMA systemin the MS 2 Initialization State. Paging channel processing refers tothe MS 2 monitoring the paging channel or the forward common controlchannel (F-CCCH) to receive overhead and mobile-directed messages fromthe BS 6 in the Idle State. Access channel processing refers to the MS 2sending messages to the BS 6 on the access channel or the Enhancedaccess channel in the System Access State, with the BS 6 alwayslistening to these channels and responding to the MS on either a pagingchannel or the F-CCCH. Traffic channel processing refers to the BS 6 andMS 2 communicating using dedicated forward and reverse traffic channelsin the MS 2 control on Traffic Channel State, with the dedicated forwardand reverse traffic channels carrying user information, such as voiceand data.

FIG. 5 illustrates the Initialization State of a MS 2. TheInitialization State includes a System Determination Substate, PilotChannel Acquisition, Sync Channel Acquisition, a Timing Change Substateand a Mobile Station Idle State.

System Determination is a process by which the MS 2 decides from whichsystem to obtain service. The process could include decisions such asanalog versus digital, cellular versus PCS, and A carrier versus Bcarrier. A custom selection process may control System determination. Aservice provider using a redirection process may also control SystemDetermination. After the MS 2 selects a system, it must determine onwhich channel within that system to search for service. Generally the MS2 uses a prioritized channel list to select the channel.

Pilot Channel Acquisition is a process whereby the MS 2 first gainsinformation regarding system timing by searching for usable pilotsignals. Pilot channels contain no information, but the MS 2 can alignits own timing by correlating with the pilot channel. Once thiscorrelation is completed, the MS 2 is synchronized with the sync channeland can read a sync channel message to further refine its timing. The MS2 is permitted to search up to 15 seconds on a single pilot channelbefore it declares failure and returns to System Determination to selecteither another channel or another system. The searching procedure is notstandardized, with the time to acquire the system depending onimplementation.

FIG. 6 illustrates the System Access State. The first step in the systemaccess process is to update overhead information to ensure that the MS 2is using the correct Access channel parameters, such as initial powerlevel and power step increments. A MS 2 randomly selects an accesschannel and transmits without coordination with the BS 6 or other MS.

FIG. 7 illustrates a Mobile Traffic Channel state. The Mobile TrafficChannel state includes Service Negotiation, an Active Mode and a ControlHold Mode.

Service Negotiation is a process by which the MS 2 and the BS 6negotiate which service options will be used during a call and how theradio channel will be configured to support those services, Typically,Service Negotiation occurs at the beginning of a call, although it mayoccur at any time during a call if necessary. FIG. 15 illustrates theService Negotiation process between a BS 6 and MS 2.

While operating in the Traffic Channel Substate, the MS 2 may operate ineither the Active Mode or the Control Hold Mode. In the Active Mode, theReverse Pilot channel is active, along with either the R-FCH, R-DCCH.R-SCH or R-PDCH may be active if high-speed data is available. In theControl Hold Mode, only the Reverse Pilot channel is transmitted and itmay be operating in a gated mode, such as ½ or ¼, to reduce transmitpower.

The MS 2 enters the Control Hold Mode when directed by the BS 6 to stoptransmitting on R-FCH and R-DCCH. While in the Control Hold Mode, if theMS 2 has user data to send, it may request that supplemental channels beassigned. If the BS 6 grants this assignment, the MS 2 transitions backto the Active Mode and resumes transmitting the continuous Pilot channeland either the R-FCH or R-DCCH channel.

The Multiplexing and QoS Control sublayer 34 has both a transmittingfunction and a receiving function. The transmitting function combinesinformation from various sources, such as Data Services 61, SignalingServices 63 or Voice Services 62, and forms Physical layer SDUs andPDCHCF SDUs for transmission. The receiving function separates theinformation contained in Physical Layer 21 and PDCHCF SDUs and directsthe information to the correct entity, such as Data Services 61, UpperLayer Signaling 63 or Voice Services 62.

The Multiplexing and QoS Control sublayer 34 operates in timesynchronization with the Physical Layer 21. If the Physical Layer 21 istransmitting with a non-zero frame offset, the Multiplexing and QoSControl sublayer 34 delivers Physical Layer SDUs for transmission by thePhysical Layer at the appropriate frame offset from system time.

The Multiplexing and QoS Control sublayer 34 delivers a Physical Layer21 SDU to the Physical Layer using a physical-channel specific serviceinterface set of primitives. The Physical Layer 21 delivers a PhysicalLayer SDU to the Multiplexing and QoS Control sublayer 34 using aphysical channel specific Receive Indication service interfaceoperation.

The SRBP Sublayer 35 includes the Sync Channel, Forward Common ControlChannel, Broadcast Control Channel, Paging Channel and Access ChannelProcedures.

The LAC Sublayer 32 provides services to Layer 3 60. SDUs are passedbetween Layer 3 60 and the LAC Sublayer 32. The LAC Sublayer 32 providesthe proper encapsulation of the SDUs into LAC PDUs, which are subject tosegmentation and reassembly and are transferred as encapsulated PDUfragments to the MAC Sublayer 31.

Processing within the LAC Sublayer 32 is done sequentially, withprocessing entities passing the partially formed LAC PDU to each otherin a well-established order. SDUs and PDUs are processed and transferredalong functional paths, without the need for the upper layers to beaware of the radio characteristics of the physical channels. However,the upper layers could be aware of the characteristics of the physicalchannels and may direct Layer 2 30 to use certain physical channels forthe transmission of certain PDUs.

A 1xEV-DO system is optimized for packet data service and characterizedby a single 1.25 MHz carrier (“1x”) for Data Only or Data Optimized(“DO”), Furthermore, there is a peak data rate of up to 4.9152 Mbps onthe Forward Link and up to 1.8432 Mbps on the Reverse Link. Moreover1xEV-DO provides separated frequency bands and internetworking with a 1xSystem. FIG. 8 illustrates a comparison of cdma2000 for 1x and 1xEV-DO.

In a cdma2000 system, there are concurrent services, whereby voice anddata are transmitted together at a maximum data rate of 614.4 kbps and307.2 kbps in practice. An MS 2 communicates with the MSC 5 for voicecalls and with the PDSN 12 for data calls. CDMA2000 is characterized bya fixed rate with variable power with a Walsh-code separated forwardtraffic channel.

In a 1xEV-DO system, the maximum data rate is 4.9152 Mbps and there isno communication with the circuit-switched core network 7. 1xV-DO ischaracterized by fixed power and a variable rate with a single forwardchannel that is time division multiplexed.

FIG. 9 illustrates a 1xEV-DO architecture. In a 1xEV-DO system, a frameconsists of 16 slots, with 600 slots/sec, and has a duration of 26.67ms, or 32,768 chips. A single slot is 1.6667 ms long and has 2048 chips.A control/traffic channel has 1600 chips in a slot, a pilot channel has192 chips in a slot and a MAC channel has 256 chips in a slot. A 1xEV-DOsystem facilitates simpler and faster channel estimation and timesynchronization.

FIG. 10 illustrates a 1xEV-DO system default protocol architecture. FIG.11 illustrates a 1xEV-DO system non-default protocol architecture.

Information related to a session in a 1xEV-DO system includes a set ofprotocols used by an MS 2, or Access Terminal (AT), and a BS 6, orAccess Network (AN), over an airlink, a Unicast Access TerminalIdentifier (UATI), configuration of the protocols used by the AT and ANover the airlink and an estimate of the current AT location.

The Application Layer provides best effort, whereby the message is sentonce, and reliable delivery, whereby the message can be retransmittedone or more times. The Steam Layer provides the ability to multiplex upto 4 (default) or 244 (non-default) application streams for one AT 2.

The Session Layer ensures the session is still valid and manages closingof session, specifies procedures for the initial UATI assignment,maintains AT addresses and negotiates/provisions the protocols usedduring the session and the configuration parameters for these protocols.

FIG. 12 illustrates the establishment of a 1xEV-DO session. Asillustrated in FIG. 12, establishing a session includes addressconfiguration, connection establishment, session configuration andexchange keys.

Address configuration refers to an Address Management protocol assigninga UATI and Subnet mask. Connection establishment refers to ConnectionLayer protocols setting up a radio link, Session configuration refers toa Session Configuration Protocol configuring all protocols. Exchangekeys refer to a Key Exchange protocol in the Security Layer setting upkeys for authentication.

A “session’ refers to the logical communication link between the AT 2and the RNC, which remains open for hours, with a default of 54 hours. Asession lasts until the PPP session is active as well. Sessioninformation is controlled and maintained by the RNC in the AN 6.

When a connection is opened, the AT 2 can be assigned the forwardtraffic channel and is assigned a reverse traffic channel and reversepower control channel. Multiple connections may occur during singlesession. There are two connection states in a 1xEV-DO system, a closedconnection and an open connection.

A closed connection refers to a state where the AT 2 is not assigned anydedicated air-link resources and communications between the AT and AN 6are conducted over the access channel and the control channel. An openconnection refers to a state where the AT 2 can be assigned the forwardtraffic channel, is assigned a reverse power control channel and areverse traffic channel and communication between the AT 2 and AN 6 isconducted over these assigned channels as well as over the controlchannel.

The Connection Layer manages initial acquisition of the network, settingan open connection and closed connection and communications.Furthermore, the Connection Layer maintains an approximate AT 2 locationin both the open connection and closed connection and manages a radiolink between the AT 2 and the AN 6 when there is an open connection.Moreover, the Connection Layer performs supervision in both the openconnection and closed connection, prioritizes and encapsulatestransmitted data received from the Session Layer, forwards theprioritized data to the Security Layer and decapsulates data receivedfrom the Security Layer and forwards it to the Session Layer.

FIG. 13 illustrates Connection Layer Protocols. As illustrated in FIG.13, the protocols include an Initialization State, an Idle State and aConnected State.

In the Initialization State, the AT 2 acquires the AN 6 and activatesthe initialization State Protocol. In the Idle State, a ClosedConnection is initiated and the Idle State Protocol is activated. In theconnected State, an open connection is initiated and the Connected StateProtocol is activated.

The Initialization State Protocol performs actions associated withacquiring an AN 6. The Idle State Protocol performs actions associatedwith an AT 2 that has acquired an AN 6, but does not have an openconnection, such as keeping track of the AT location using a RouteUpdate Protocol. The Connected State Protocol performs actionsassociated with an AT 2 that has an open connection, such as managingthe radio link between the AT and AN 6 and managing the proceduresleading to a closed connection. The Route Update Protocol performsactions associated with keeping track of the AT 2 location andmaintaining the radio link between the AT and AN 6. The Overhead MessageProtocol broadcasts essential parameters, such as QuickConfig,SectorParameters and AccessParameters message, over the Control channel.The Packet Consolidation Protocol consolidates and prioritizes packetsfor transmission as a function of their assigned priority and the targetchannel as well as providing packet de-multiplexing on the receiver.

The Security Layer includes a key exchange function, authenticationfunction and encryption function. The key exchange function provides theprocedures followed by the AN 2 and AT 6 for authenticating traffic. Theauthentication function provides the procedures followed by the AN 2 andAT 6 to exchange security keys for authentication and encryption. Theencryption function provides the procedures followed by the AN 2 and AT6 for encrypting traffic.

The 1xEV-DO forward link is characterized in that no power control andno soft handoff is supported for the packet data channel (also referredto as the forward traffic channel). The AN 6 transmits at constant powerand the AT 2 requests variable rates on the forward link. Becausedifferent users may transmit at different times in TDM, it is difficultto implement diversity transmission from different BS's 6 that areintended for a single user.

In the MAC Layer, two types of messages originated from higher layersare transported across the physical layer, specifically a user datamessage and a signaling message. Two protocols are used to process thetwo types of messages, specifically a forward traffic channel MACProtocol for the user data message and a control channel MAC Protocol,for the signaling message.

The Physical Layer 21 is characterized by a spreading rate of 1.2288Mcps, a frame consisting of 16 slots and 26.67 ms, with a slot of 1.67ms and 2048 chips. The forward link channel includes a pilot channel, aforward traffic channel or control channel and a MAC channel.

The pilot Channel is similar to the to the cdma2000Pilot channel in thatit comprises all “0” information bits and Walsh-spreading with W0 with192 chips for a slot.

The forward traffic channel is characterized by a data rate that variesfrom 38.4 kbps to 2.4576 Mbps or from 4.8 kbps to 3.072 Mbps. PhysicalLayer packets can be transmitted in 1 to 16 slots and the transmit slotsuse 4-slot interlacing when more than one slot is allocated. If ACK isreceived on the reverse link ACK channel before all of the allocatedslots have been transmitted, the remaining slots shall not betransmitted.

The control channel is similar to the sync channel and paging channel incdma2000. The control channel is characterized by a period of 256 slotsor 427.52 ms, a Physical Layer packet length of 1024 bits or 128, 256,512 and 1024 bits and a data rate of 38.4 kbps or 76.8 kbps or 19.2kbps, 38.4 kbps or 76.8 kbps.

The traffic operations supported by the forward link include Data RateControl (DRC) reporting, Scheduling at the BS 6, data transmission tothe selected user and ACK/NAK.

Data Rate Control (DRC) reporting facilitates an AT 2 reporting DRC asoften as once every 1.67 ms. Each active AT 2 measures its radioconditions and provides the measurements to the BS 6, with a data rateof (600/DRCLength) DRC values per second. Parameters reported includeDRCLength, DRCGating, DRCLock channel, DRCOffset and DRC Channel.

DRCLength determines how often DRC values are computed by the AT 2 anddetermines the gain for the DRC channel, with the lowest for 8 slots.Possible values are 1, 2, 4 or 8 slots.

DRCGating determines whether the AT 2 sends the DRC values continuouslyor discontinuously. Possible values are 0x00 for continuous and 0x01 fordiscontinuous.

DRCOffset facilitates computing the transmitted DRC by subtracting theDRCOffset from the tentative DRC and is suitable for a more realisticenvironment.

DRC Channel is used by the AT 2 to indicate the selected serving sectorand the requested data rate on the forward traffic channel to the AN 6.The requested data rate is mapped into a 4-digit DRC value, with an8-ary Walsh function corresponding to the selected serving sector usedto spread the DRC channel transmission. The DRCCover from the ForwardTraffic channel MAC protocol defines the cover mapping. DRC values aretransmitted at a data rate of 600/DRCLength DRC values per second, witha maximum rate of 600 per second and a minimum rate of 75 per second.

The 1xEV-DO reverse link is characterized in that the AN 6 can powercontrol the reverse link by using reverse power control and more thanone AN can receive the AT's 2 transmission via soft handoff.Furthermore, there is no TDM on the reverse link, which is channelizedby Walsh code using a Long PN code.

In the reverse link, two MAC Layer protocols are used to process twotypes of messages. A reverse traffic channel MAC protocol is used toprocess user data messages and an access channel MAC protocol is used toprocess signaling messages.

Using the reverse traffic channel MAC protocol, the AN 6 providesinformation to the AT 2 including BroadcastReverseRateLimit,UnicastReverseRateLimit, Reverse Activity Bit, Transition Probabilitymatrix and Rate Parameters. Reverse link channels include reversetraffic channels and access channels.

Reverse traffic channels include a data channel, pilot channel, MACchannel and ACK channel. Primary and auxiliary pilot channels may beprovided.

The MAC channel further includes a Reverse Rate Indicator (RRI) channel,Data Rate Control (DRC) channel and Data Source Control (DSC) channel.Access channels include a pilot channel and data channel.

As the number of carriers grows, so does the overhead. For example, thelevel of overhead for a Traffic Channel Assignment (TCA) message, whichis transmitted by AN to manage AT's active set in the connected state,can assume a size greater than 300 bits when there are 2 carriers and anactive set of 2 or a size on the order of 2000 bits when there are 15carriers and an active set of 2. Since the TCA message may be sentfrequently, such as every few seconds, much of the information remainsstatic while only a small portion changes. Therefore, conventionalmethods, which repeat all the information whether static or changed, areinefficient.

Therefore, there is a need for a more efficient means to communicateinformation, most of which is static. The present invention addressesthis and other needs.

SUMMARY OF THE INVENTION

Features and advantages of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings. Theinvention is directed to provide a method and apparatus to reduce theoverhead of frequently sent signaling messages.

In one aspect of the present invention, a method of providing signalinginformation in a multi-carrier mobile communication system is provided.The method includes generating a signaling message by concatenating aplurality of fields and transmitting the signaling message, wherein atleast two of the plurality of fields convey similar information, a firstof the at least two fields including the information and the second ofthe at least two fields including a flag, the flag indicating that avalue of the second of the at least two fields is the same as theinformation in the first of the at least two fields.

It is contemplated that the signaling message is a traffic channelassignment message. It is further contemplated that the second of the atleast two fields includes a flag indicating that a value of a pluralityof consecutively concatenated fields is the same as the information in aprevious plurality of consecutively concatenated fields.

In another aspect of the present invention, a method of providingsignaling information in a mobile communication system is provided. Themethod includes receiving a signaling message including a plurality ofconcatenated fields, determining that at least one of the plurality offields includes a flag, the flag indicating that a value of the field isthe same as information in a previous field and setting the value of theat least one of the plurality of fields to the information of theprevious field.

It is contemplated that the signaling message is a traffic channelassignment message. It is further contemplated that the method furtherincludes determining that the flag indicates that a value of a pluralityof consecutively concatenated fields is the same as the information in aprevious plurality of consecutively concatenated fields and setting thevalue of the plurality of consecutively concatenated fields to theinformation in the previous plurality of consecutively concatenatedfields.

In another aspect of the present invention, a method of providingsignaling information in a mobile communication system is provided. Themethod includes generating a first signaling message and a secondsignaling message, each message including at least one field andtransmitting the first signaling message and the second signalingmessage, wherein at least one field in the second signaling messageincludes a flag, the flag indicating that a value of the at least onefield in the second signaling message is the same as information in acorresponding at least one field in the first signaling message suchthat the second signaling message is shorter than the first signalingmessage.

It is contemplated that the at least one field in the second signalingmessage includes a flag indicating that a value of a plurality ofconsecutively concatenated fields in the second signaling message is thesame as the information in a corresponding plurality of consecutivelyconcatenated fields in the first signaling message. It is furthercontemplated that the first and second signaling messages each furthercomprise an incremental message sequence number, the sequence number ofthe second signaling message incremented from the sequence number of thefirst signaling message.

It is contemplated that the method further includes re-transmitting thesecond signaling message if it is determined that the second signalingmessage was not received, the sequence number of the resent secondsignaling message remaining unchanged. It is further contemplated thatthe method further includes determining whether the value of the leastone field in the first signaling message is still applicable aftertransmitting the second signaling message.

It is contemplated that the method further includes generating at leasta third signaling message, the third signaling message including the atleast one field including the flag indicating that the value of the atthe at least one field is the same as information in the correspondingat least one field in the first signaling message such that the thirdsignaling message is shorter than the first signaling message andtransmitting the at least a third signaling message. It is furthercontemplated that the first and second signaling messages each furthercomprise a message identification field.

It is contemplated that the message identification fields of the firstand second signaling messages are the same. It is further contemplatedthat the message identification fields of the first and second signalingmessages are different.

In another aspect of the present invention, a method of providingsignaling information in a mobile communication system is provided. Themethod includes receiving a first signaling message and a secondsignaling message, each of the signaling messages including at least onefield, determining that at least one field in the second signalingmessage includes a flag, the flag indicating that a value of the atleast one field in the second signaling message is the same asinformation in a corresponding at least one field in the first signalingmessage and setting the value of the at least one field in the secondsignaling message to the information in the corresponding at least onefield in the first signaling message. Preferably, the method furtherincludes determining that the at least one field in the second signalingmessage includes a flag indicating that a value of a plurality ofconsecutively concatenated fields in the second signaling message is thesame as the information in a corresponding plurality of consecutivelyconcatenated fields in the first signaling message and setting the valueof the plurality of consecutively concatenated fields in the secondsignaling message to the information in the corresponding plurality ofconsecutively concatenated fields in the first signaling message.

In another aspect of the present invention, a method of providingsignaling information in a mobile communication system is provided. Themethod includes generating a signaling message including at least onefield including a flag, the flag indicating whether a certain feature isactivated and transmitting the signaling message, wherein, if the flagindicates that the certain feature is activated, the signaling messageincludes at least one additional field related to the certain featureand, if the flag indicates that the certain feature is not activated,the signaling message includes no additional field related to thecertain feature such that the signaling message is shorter if thecertain feature is not activated.

In another aspect of the present invention, a method of providingsignaling information in a mobile communication system is provided. Themethod includes receiving a signaling message including at least onefield including a flag, the flag indicating whether a certain feature isactivated and extracting at least one additional field related to thecertain feature from the message if the flag indicates that the certainfeature is activated and extracting no additional field related to thecertain feature from the message if the flag indicates that the certainfeature is not activated such that less fields are extracted from thesignaling message if the certain feature is not activated.

In another aspect of the present invention, a mobile terminal isprovided. The mobile terminal includes a transmitting/receiving unitadapted to transmit and receive signaling messages, a display unitadapted to display user interface information, an input unit adapted toinput user data and a processing unit adapted to generate and controlthe transmitting/receiving unit to transmit a signaling message, thesignaling message generated by concatenating a plurality of fields suchthat at least two of the plurality of fields convey similar information,a first of the at least two fields including the information and thesecond of the at least two fields including a flag, the flag indicatingthat a value of the second of the at least fields is the same as theinformation in the first of the at least two fields.

It is contemplated that the second of the at least two fields includes aflag indicating that a value of a plurality of consecutivelyconcatenated fields is the same as the information in a previousplurality of consecutively concatenated fields. It is furthercontemplated that the processing unit is further adapted to receive asignaling message including a plurality of concatenated fields,determine that at least one of the plurality of fields includes a flag,the flag indicating that a value of the field is the same as informationin a previous field and set the value of the at least one of theplurality of fields to the information of the previous field.

It is contemplated that the signaling message is a traffic channelassignment message. It is further contemplated that the processing unitis further adapted to determine that the flag indicates that a value ofa plurality of consecutively concatenated fields is the same as theinformation in a previous plurality of consecutively concatenated fieldsand set the value of the plurality of consecutively concatenated fieldsto the information in the previous plurality of consecutivelyconcatenated fields.

It is contemplated that the processing unit is further adapted togenerate and transmit a first signaling message including at least onefield and generate and transmit a second signaling message including atleast one field, wherein the at least one field in the second signalingmessage includes a flag indicating that a value of the at least onefield in the second signaling message is the same as information in acorresponding at least one field in the first signaling message suchthat the second signaling message is shorter than the first signalingmessage. It is further contemplated that the at least one field in thesecond signaling message includes a flag indicating that a value of aplurality of consecutively concatenated fields in the second signalingmessage is the same as the information in a corresponding plurality ofconsecutively concatenated fields in the first signaling message.

It is contemplated that the processing unit is further adapted toinclude an incremental message sequence number in the first and secondsignaling messages such that the sequence number of the second signalingmessage is incremented from the sequence number of the first signalingmessage. It is further contemplated that the processing unit is furtheradapted to re-transmit the second signaling message if it is determinedthat the second signaling message was not received, the sequence numberof the resent second signaling message remaining unchanged.

It is contemplated that the processing unit is further adapted todetermine whether the value of the least one field in the firstsignaling message is still applicable after transmitting the secondsignaling message. It is further contemplated that the processing unitis further adapted to generate and transmit at least a third signalingmessage, the third signaling message including the at least one fieldincluding the flag indicating that the value of the at the at least onefield is the same as information in the corresponding at least one fieldin the first signaling message such that the third signaling message isshorter than the first signaling message.

It is contemplated that the first and second signaling messages eachfurther comprise a message identification field. It is furthercontemplated that the message identification fields of the first andsecond signaling messages are the same.

It is contemplated that the message identification fields of the firstand second signaling messages are different. It is further contemplatedthat the processing unit is further adapted to receive a first signalingmessage and a second signaling message, each of the signaling messagesincluding at least one field, determine that at least one field in thesecond signaling message includes a flag, the flag indicating that avalue of the at least one field in the second signaling message is thesame as information in a corresponding at least one field in the firstsignaling message and set the value of the at least one field in thesecond signaling message to the information in the corresponding atleast one field in the first signaling message.

It is contemplated that the processing unit is further adapted todetermine that the at least one field in the second signaling messageincludes a flag indicating that a value of a plurality of consecutivelyconcatenated fields in the second signaling message is the same as theinformation in a corresponding plurality of consecutively concatenatedfields in the first signaling message and set the value of the pluralityof consecutively concatenated fields in the second signaling message tothe information in the corresponding plurality of consecutivelyconcatenated fields in the first signaling message. It is furthercontemplated that the processing unit is further adapted to generate andtransmit a signaling message including at least one field, the at leastone filed including a flag indicating whether a certain feature isactivated, wherein the signaling message includes at least oneadditional field related to the certain feature if the flag indicatesthat the certain feature is activated and the signaling message includesno additional field related to the certain feature if the flag indicatesthat the certain feature is not activated such that the signalingmessage is shorter if the certain feature is not activated. Preferably,the processing unit is further adapted to receive a signaling messageincluding at least one field including a flag indicating whether acertain feature is activated and extract at least one additional fieldrelated to the certain feature from the message if the flag indicatesthat the certain feature is activated and extract no additional fieldrelated to the certain feature from the message if the flag indicatesthat the certain feature is not activated such that less fields areextracted from the signaling message if the certain feature is notactivated.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. It is to beunderstood that both the foregoing general description and the followingdetailed description of the present invention are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

These and other embodiments will also become readily apparent to thoseskilled in the art from the following detailed description of theembodiments having reference to the attached figures, the invention notbeing limited to any particular embodiments disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. Features, elements, and aspects of the invention that arereferenced by the same numerals in different figures represent the same,equivalent, or similar features, elements, or aspects in accordance withone or more embodiments.

FIG. 1 illustrates wireless communication network architecture.

FIG. 2A illustrates a CDMA spreading and de-spreading process.

FIG. 2B illustrates a CDMA spreading and de-spreading process usingmultiple spreading sequences.

FIG. 3 illustrates a data link protocol architecture layer for acdma2000 wireless network.

FIG. 4 illustrates cdma2000 call processing.

FIG. 5 illustrates the cdma2000 initialization state.

FIG. 6 illustrates the cdma2000 system access state.

FIG. 7 illustrates the cdma2000 mobile traffic channel state.

FIG. 8 illustrates a comparison of cdma2000 for 1x and 1xEV-DO.

FIG. 9 illustrates a network architecture layer for a 1xEV-DO wirelessnetwork.

FIG. 10 illustrates 1xEV-DO default protocol architecture.

FIG. 11 illustrates 1xEV-DO non-default protocol architecture.

FIG. 12 illustrates 1xEV-DO session establishment.

FIG. 13 illustrates 1xEV-DO connection layer protocols.

FIGS. 14A-C illustrate a TCA message according to one embodiment of thepresent invention.

FIGS. 15A-C illustrate a TCA message according to another embodiment ofthe present invention

FIG. 16 illustrates a block diagram of a mobile station or accessterminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method and apparatus to reduce theoverhead of frequently sent signaling messages. Although the presentinvention is illustrated with respect to a mobile terminal and accessnetwork, it is contemplated that the present invention may be utilizedanytime it is desired to reduce the overhead of frequently sentsignaling messages in communication devices.

One method to reduce the overhead of frequently sent signaling messagesis to send a Lightweight version of a signaling message instead ofsending a self-contained signaling message, or full version signalingmessage, when information is unchanged. By omitting the unchangedinformation that was already conveyed in either a previous a fullversion or lightweight version a signaling message, the size of thelightweight signaling message is reduced.

The order of delivery for the same type of messages to a receiver ismaintained. As used herein, “TCA message” refers to a full versionsignaling message and “TCA Lite message” refers to a lightweightsignaling message. The TCA message and TCA Lite message may be themessages with the same message id, but the later TCA Lite message hasflags indicating the omission of the information that was alreadyconveyed in the TCA message.

The use of lightweight signaling messages, which omits the informationconveyed by a previous message, may present problems if the receivermisses the previous signaling message, since the transmitter may assumethat the receiver has received the message. If the next message is afull version signaling message, no problem occurs. However, if thefollowing message is a lightweight signaling message, there is apossibility that information indicated in the previous signalingmessage, but absent in the next lightweight signaling message, aremissed by the receiver.

Therefore, a mechanism to detect missed messages is provided. Anincremental message sequence number may be used in order to detectmissed messages.

Furthermore, ambiguity may exist if a TCA Lite message is sent withouthaving received an acknowledgement, such as TrafficChannelComplete(TCC), for a first signaling message, either a TCA or TCA Lite message.Ambiguity may occur since the AT 2 may not know how to interpret the TCALite message in the absence of the first signaling message.

For example, if a TCC for a first TCA message or TCA Lite message isreceived, there is no problem. However, if a TCC for a first TCA messageor TCA Lite message is not received, then the AT 2 will discard thesubsequent TCA Lite message in the absence of decoding the first TCAmessage or TCA Lite message.

Potential ambiguity may be avoided in two ways when a TCA Life messagemust be sent before a TCC for a previous TCA message or TCA Lite messageis received and while a timer is active. A simple option is to send thefull version signaling message. A slightly more complication option isto send another lightweight signaling message. However, it should benoted that the likelihood of sending two signaling messages so closetogether is very low.

Sending a TCA message in place of a TCA Lite message if anacknowledgment for a first TCA message or TCA Lite message has not yetbeen received provides the AT 2 with the entire signaling information.If a TCA Lite message is sent and a TC Complete (acknowledgement) is notreceived, then, the TCA Lite message should be sent with the samesequence number if it is sent again.

Another method to reduce the overhead of frequently sent signalingmessages is to include flags to indicate whether features usedinfrequently are activated by the signaling message. If a feature is notactivated, the related parameters can be omitted from the signalingmessage.

Another method to reduce the overhead of frequently sent signalingmessages is to iterate components in a signaling message with the sameor similar parameters in the same message such that the same informationcan be omitted by using a flag indicating that the value of one or morefields is the same as in a previous iteration. Note this approach may beapplied to the original signaling message as well as the lightweightsignaling message in order to reduce overhead.

Another method to reduce the overhead of frequently sent signalingmessages is to use the TCA Lite message to convey the information sentin a conventional TCA message. In this way, the TCA Lite message may beused to either replace the current TCA message or as an additional TCAmessage.

Another method to reduce the overhead of frequently sent signalingmessages is a differential approach whereby a new signaling message iscompared to a previously sent signaling message. The difference betweenthe two signaling messages can be sent such that the AT 2 canreconstruct the new signaling message based on the previously receivedsignaling message.

Another method to reduce the overhead of frequently sent signalingmessages is to create a new and separate signaling message, or “TCASpecial x” message, which can be used to send specific portions of thefull TCA message. The “x” is used to denote different TCA specialmessages. For example, a TCA special message can be designed to sendonly those parameters related to active set management. Alternately, aTCA Lite message having special flags may be used to implement the TCAspecial message instead of creating a separate message.

The network may periodically send the full version TCA message to ensurethat the AT 2 has the correct values. In this way, additional securityis may be provided for any of the methods described herein.

FIGS. 14A-C illustrate a lightweight TrafficChannelAssignment (TCA,) orTCA Lite, message. The TCA Lite message includes all the fieldsindicated in FIG. 14A. Furthermore, each TCA Lite message includes “N”occurrences of the DSCIncluded and DSC fields, where “N” is the numberof SofterHandoff fields set to “0” in the “NumSectors” occurrences ofthe SectorInformation record. FIGS. 15A-C illustrate a LightweightTrafficChannelAssignment (TCA,) or TCA Lite, message according toanother embodiment of the invention.

The TCA Lite message may be used as a replacement for regular full TCAmessage such that there is only one format, one message ID. Alternately,the TCA Lite message may be separately defined with a different messageID such that the extra flags in the TCA Lite message are not in the fullregular version TCA message.

The TCA Lite message further includes the SectorInformation recordillustrated in FIG. 14B repeated according to the NumSectors field suchthat there are “NumSectors” occurrences of the SectorInformation record.Furthermore, the TCA Lite message includes the ActiveSetParametersrecord illustrated in FIG. 14C repeated according to theNumForwardChannels field such that there are “NumForwardChannels”occurrences of the ActiveSetParameters record.

The TCA Lite message may have the same or different MessageID field asthe full version TCA message. If the TCA Lite message has a differentMessageID field in order to be distinguishable from the regular TCAmessage, it shares MessageSequence space with the regular TCA message.Therefore, the value of MessageSequence is incremented in a subsequentTCA or TCA Lite message from the value in the previous message, which iseither a TCA or a TCA Lite message.

The ActiveSetParameters record includes all fields from AssignedChannelthrough MACIndex as illustrated in FIG. 14C. Some of the fields of theActiveSetParameters record are repeated according to the values of otherfields in the TCA Lite message. Each of the “NumForwardChannels”occurrences of the ActiveSetParameters record includes “NumSectors”occurrences of the SectorConfigurationIncluded through MACIndex fields.

The DSCChannelGain and FrameOffset values are omitted ifNext2FieldsIncluded is “0.” Setting Next2FieldsIncluded to “0” indicatesthat the values are the same as in the previous message.

The RAChannelGain through SofterHandoff values are omitted ifNext3FieldsIncluded is “0.” Setting Next3FieldsIncluded to “0” indicatesthat the values are the same as in the previous message for the sectorwith the same PilotPN.

The DSC values are omitted if DSCIncluded is “0.” Setting DSC includedto “0” indicates that the values are the same as in the previous messagefor the same cell.

All the fields between the ChannelConfigurationIncluded andReverseChannel fields may be omitted if ChannelConfigurationIncluded is“0.” Setting ChannelConfigurationIncluded to “0” indicates that thecarrier configuration is the same as specified in the previous message.

If ReverseChannelDroppingRankIncluded is “0,” thenReverseChannelDroppingRank for the carrier is the same as specified inthe previous message. Furthermore, ReverseChannelDroppingRankIncluded isnot included if there is no reverse link configured for the specifiedforward link carrier.

If SectorConfigurationIncluded is “0,” then all the fields that followfor the sector of the specified carrier may be omitted. SettingSectorConfigurationIncluded to “0” indicates that the values of thefields are the same as specified in the previous message.

The FeedbackMultiplexingIndex, FeedbackReverseChannelIndex,ReverseChannelConfiguration and ReverseChannel fields may be omitted ifSymmetricFeedbackReverseChannel is set to “1” regardless of the valuesof the ChannelConfigurationIncluded or ConfigurationsameasPrevChannelfields. Setting SymmetricFeedbackReverseChannel to “1” indicates therewill be no feedback multiplexing and the feedback will always be carriedon a paired reverse link.

If the SymmetricFeedbackReverseChannel is set to “0,” thenChannelConfigurationIncluded indicates whether theFeedbackMultiplexingIndex through ReverseChannel fields are included. Ifthe ConfigurationsameasPrevChannel field is present, then the valueindicates whether all following fields until ReverseChannelConfigurationfield are included.

The DSCSameAsThisForwardChannel field may be omitted if MultipleDSC is“1.” Setting MultipleDSC to “1” indicates that the values of the fieldis the same as specified in the previous message.

If ConfigurationsameasPrevChannel is “1,” then all the following fieldsfrom DSCSameAsThisForwardChannel through ReverseChannelConfiguration,inclusive, may be omitted. Setting ConfigurationsameasPrevChannel to “1”indicates that the same carrier configuration as specified in thecarrier previously iterated is used.

FIG. 16 illustrates a block diagram of a mobile station (MS) or accessterminal 100 according to one embodiment of the present invention. TheAT 100 includes a processor (or digital signal processor) 110, RF module135, power management module 105, antenna 140, battery 155, display 115,keypad 120, memory 130, SIM card 125 (which may be optional), speaker145 and microphone 150.

A user enters instructional information, such as a telephone number, forexample, by pushing the buttons of a keypad 120 or by voice activationusing the microphone 150. The microprocessor 110 receives and processesthe instructional information to perform the appropriate function, suchas to dial the telephone number. Operational data may be retrieved fromthe Subscriber Identity Module (SIM) card 125 or the memory module 130to perform the function. Furthermore, the processor 110 may display theinstructional and operational information on the display 115 for theuser's reference and convenience.

The processor 110 issues instructional information to the RF module 135,to initiate communication, for example, by transmitting radio signalscomprising voice communication data. The RF module 135 includes areceiver and a transmitter to receive and transmit radio signals. Anantenna 140 facilitates the transmission and reception of radio signals.Upon receiving radio signals, the RF module 135 may forward and convertthe signals to baseband frequency for processing by the processor 110.The processed signals would be transformed into audible or readableinformation outputted via the speaker 145, for example. The processor110 also includes the protocols and functions necessary to perform thevarious processes described herein with regard to cdma2000 or 1xEV-DOsystems.

The processor 110 is adapted to perform the methods disclosed herein forreducing overhead in signaling messages. The processor generates andcontrols the RF module 135 to receive conventional TCA and TCA Litemessages, as illustrated in FIGS. 14A-C, process the messages andtransmit an acknowledgement message.

Although the present invention is described with reference to cdma2000,1xEV-DO and cdma2000 NxEV-DO, it may also be applied to other applicablecommunication systems.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuredescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

1. A method of generating a message for transmission in a multi-carriermobile communication system, the method comprising: generating, at abase station, a traffic channel assignment message comprising aNumSubActiveSets field indicating a number of occurrences of sub-activeset parameters records to be included in the traffic channel assignmentmessage, wherein a first record of the sub-active set parameters recordscomprises a flag and three adjacent fields, and a second record of thesub-active set parameters records comprises a flag and three adjacentfields; and setting the flag of the second record of the sub-active setparameters records to a predetermined state when a value of each of thethree adjacent fields of the second record of the sub-active setparameters records is the same as a corresponding field of the threeadjacent fields of the first record of the sub-active set parametersrecords.
 2. The method according to claim 1, wherein each of the threeadjacent fields of the first record of the sub-active set parametersrecords is respectively defined by a data rate control (DRC) length(DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 3. The method according to claim 2, wherein theDRCLength field is 0 or 2 bits, the DRCChannelGainBase field is 0 or 6bits, and the ACKChannelGain field is 0 or 6 bits.
 4. The methodaccording to claim 1, wherein each of the three adjacent fields of thefirst record of the sub-active set parameters records is respectivelydefined by a data rate control (DRC) length (DRCLength) field, a datarate control (DRC) channel gain base (DRCChannelGainBase) field, and anacknowledgement channel gain (ACKChannelGain) field, and wherein each ofthe three adjacent fields of the second record of the sub-active setparameters records is respectively defined by a data rate control (DRC)length (DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 5. The method according to claim 1, wherein theflag of the first record of the sub-active set parameters records is aNext3FieldsSameAsBefore flag which is immediately adjacent to the threeadjacent fields of the first record.
 6. A method of receiving signalinginformation in a multi-carrier mobile communication system, the methodcomprising: receiving, at user equipment (UE), a traffic channelassignment message comprising a NumSubActiveSets field indicating anumber of occurrences of sub-active set parameters records that areincluded in the traffic channel assignment message, wherein a firstrecord of the sub-active set parameters records comprises a flag andthree adjacent fields, and a second record of the sub-active setparameters records comprises a flag and three adjacent fields; anddetermining that the flag of the second record of the sub-active setparameters records is set to a predetermined state indicating a value ofeach of the three adjacent fields of the second record of the sub-activeset parameters records is the same as a corresponding field of the threeadjacent fields of the first record of the sub-active set parametersrecords.
 7. The method according to claim 6, wherein each of the threeadjacent fields of the first record of the sub-active set parametersrecords is respectively defined by a data rate control (DRC) length(DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 8. The method according to claim 7, wherein theDRCLength field is 0 or 2 bits, the DRCChannelGainBase field is 0 or 6bits, and the ACKChannelGain field is 0 or 6 bits.
 9. The methodaccording to claim 6, wherein each of the three adjacent fields of thefirst record of the sub-active set parameters records is respectivelydefined by a data rate control (DRC) length (DRCLength) field, a datarate control (DRC) channel gain base (DRCChannelGainBase) field, and anacknowledgement channel gain (ACKChannelGain) field, and wherein each ofthe three adjacent fields of the second record of the sub-active setparameters records is respectively defined by a data rate control (DRC)length (DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 10. The method according to claim 6, wherein theflag of the first record of the sub-active set parameters records is aNext3FieldsSameAsBefore flag which is immediately adjacent to the threeadjacent fields of the first record.
 11. A method of providing signalinginformation in a multi-carrier mobile communication system, the methodcomprising: generating, at a base station, a traffic channel assignmentmessage comprising a first field indicating a number of occurrences of aplurality of records to be included in the traffic channel assignmentmessage, wherein a first record of the plurality of records comprises aflag and three adjacent fields, and a second record of the plurality ofrecords comprises a flag and three removable fields; setting the flag ofthe second record of the plurality of records to a predetermined statewhen a value of each of the three removable fields of the second recordof the plurality of records is the same as a corresponding field of thethree adjacent fields of the first record of the plurality of records;omitting the three of removable fields of the second record of theplurality of records when the flag of the second record of the pluralityof records is set; and transmitting the traffic channel assignmentmessage to permit a receiving mobile terminal to use values of the threeadjacent fields of the first record of the plurality of records when theflag of the second record of the plurality of records has been set. 12.The method according to claim 11, wherein each of the three adjacentfields of the first record is respectively defined by a data ratecontrol (DRC) length (DRCLength) field, a data rate control (DRC)channel gain base (DRCChannelGainBase) field, and an acknowledgementchannel gain (ACKChannelGain) field.
 13. The method according to claim12, wherein the DRCLength field is 0 or 2 bits, the DRCChannelGainBasefield is 0 or 6 bits, and the ACKChannelGain field is 0 or 6 bits. 14.The method according to claim 11, wherein each of the three adjacentfields of the first record is respectively defined by a data ratecontrol (DRC) length (DRCLength) field, a data rate control (DRC)channel gain base (DRCChannelGainBase) field, and an acknowledgementchannel gain (ACKChannelGain) field, and wherein each of the threeremovable fields of the second record is respectively defined by a datarate control (DRC) length (DRCLength) field, a data rate control (DRC)channel gain base (DRCChannelGainBase) field, and an acknowledgementchannel gain (ACKChannelGain) field.
 15. The method according to claim11, wherein the flag of the first record is a Next3FieldsSameAsBeforeflag which is immediately adjacent to the three adjacent fields of thefirst record.
 16. A method of receiving signaling information in amulti-carrier mobile communication system, the method comprising:receiving, at user equipment (UE), a traffic channel assignment messagecomprising a first field indicating a number of occurrences of aplurality of records to be included in the traffic channel assignmentmessage, wherein a first record of the plurality of records comprises aflag and three adjacent fields, and a second record of the plurality ofrecords comprises a flag and three removable fields; determining thatthe flag of the second record of the plurality of records is set to apredetermined state indicating that a value of each of the threeremovable fields of the second record is the same as a correspondingfield of the three adjacent fields of the first record; and setting thevalues of the three removable fields of the second record to the valuesof the corresponding fields of the three adjacent fields of the firstrecord when the flag of the second record has been set.
 17. The methodaccording to claim 16, wherein each of the three adjacent fields of thefirst record is respectively defined by a data rate control (DRC) length(DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 18. The method according to claim 17, whereinthe DRCLength field is 0 or 2 bits, the DRCChannelGainBase field is 0 or6 bits, and the ACKChannelGain field is 0 or 6 bits.
 19. The methodaccording to claim 16, wherein each of the three adjacent fields of thefirst record is respectively defined by a data rate control (DRC) length(DRCLength) field, a data rate control (DRC) channel gain base(DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field, and wherein each of the three removable fieldsof the second record is respectively defined by a data rate control(DRC) length (DRCLength) field, a data rate control (DRC) channel gainbase (DRCChannelGainBase) field, and an acknowledgement channel gain(ACKChannelGain) field.
 20. The method according to claim 16, whereinthe flag of the first record is a Next3FieldsSameAsBefore flag which isimmediately adjacent to the three adjacent fields of the first record.